U.S. patent application number 13/678738 was filed with the patent office on 2013-07-18 for sensor arrangement for detecting muscle activity for the control of technical equipment.
This patent application is currently assigned to RSL STEEPER GROUP LIMITED. The applicant listed for this patent is RSL STEEPER GROUP LIMITED. Invention is credited to Klaus BUCHENRIEDER, Stefan HERRMANN.
Application Number | 20130184539 13/678738 |
Document ID | / |
Family ID | 47594434 |
Filed Date | 2013-07-18 |
United States Patent
Application |
20130184539 |
Kind Code |
A1 |
BUCHENRIEDER; Klaus ; et
al. |
July 18, 2013 |
Sensor Arrangement for Detecting Muscle Activity for the Control of
Technical Equipment
Abstract
A sensor arrangement for detecting muscle activity for the
control of technical equipment. When in use the arrangement covers
a region of the skin surface of a user, to provide a signal
indicative of muscle activity in a limited region for subsequent
processing. The arrangement has at least one double-differential
myoelectric sensor, together with at least one near-infrared
sensor. These are for simultaneous or time-delayed derivation of
(a) myoelectric activity and (b) the value of a parameter of the
blood (for example the blood oxygen content or the relative
quantity of haemoglobin) respectively, in the muscle, the muscles
or the tissue under the arrangement.
Inventors: |
BUCHENRIEDER; Klaus;
(Riemerling, DE) ; HERRMANN; Stefan;
(Unterhaching, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
RSL STEEPER GROUP LIMITED; |
Kent |
|
GB |
|
|
Assignee: |
RSL STEEPER GROUP LIMITED
Kent
GB
|
Family ID: |
47594434 |
Appl. No.: |
13/678738 |
Filed: |
November 16, 2012 |
Current U.S.
Class: |
600/301 ;
600/324 |
Current CPC
Class: |
A61B 5/1107 20130101;
A61B 5/04012 20130101; A61B 2562/0238 20130101; A61B 5/04888
20130101; A61F 2002/7675 20130101; A61B 5/14551 20130101; A61B
2562/046 20130101; A61B 5/6801 20130101; A61B 5/14552 20130101;
A61B 5/14546 20130101; A61F 2/72 20130101; A61B 2562/043
20130101 |
Class at
Publication: |
600/301 ;
600/324 |
International
Class: |
A61B 5/0488 20060101
A61B005/0488; A61B 5/00 20060101 A61B005/00; A61B 5/11 20060101
A61B005/11; A61B 5/04 20060101 A61B005/04; A61B 5/1455 20060101
A61B005/1455; A61B 5/145 20060101 A61B005/145 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 16, 2011 |
DE |
102011118732.8 |
Claims
1. A sensor arrangement for detecting muscle activity for the
control of technical equipment, which arrangement when in use
covers a region of the skin surface of a user, to provide a signal
indicative of muscle activity in a limited region for subsequent
processing, wherein the arrangement comprises at least one
double-differential myoelectric sensor together with at least one
near-infrared sensor for simultaneous or time-delayed derivation of
(a) myoelectric activity and (b) the value of a parameter of the
blood (for example the blood oxygen content or the relative
quantity of haemoglobin) respectively, in the muscle, the muscles
or the tissue under the arrangement.
2. A sensor arrangement according to claim 1, wherein the said at
least one near-infrared sensor comprises a near-infrared
transmitter and a plurality of near-infrared receivers, and in that
an electrode of the said at least one double-differential
myoelectric sensor, the near-infrared transmitter and the plurality
of near-infrared receivers, are arranged linearly, in an array, in
an arcuate configuration or in a circular configuration, to enable
measurement of a parameter of the blood, such as the blood oxygen
content or the relative quantity of haemoglobin, in different
depths, layers or regions from which myoelectric signals are
detected by the said electrode.
3. A sensor arrangement according to claim 1, wherein the said at
least one near-infrared sensor comprises a plurality of
near-infrared transmitters and a near-infrared receiver, and
wherein an electrode of the said at least one double-differential
myoelectric sensor the plurality of near-infrared transmitters and
the near infrared receiver, are arranged linearly, in an array, in
an arcuate configuration or in a circular configuration, to enable
a measurement of a parameter of the blood, such as the blood oxygen
content or the relative quantity of haemoglobin, in different
depths, layers or regions from which myoelectric signals are
detected by the said electrode.
4. A sensor arrangement according to claim 1, wherein the said at
least one near-infrared sensor comprises one or more near-infrared
transmitters and one or more near-infrared receivers, and wherein
an electrode of the said at least one double-differential
myoelectric sensor, the said one or more near-infrared transmitters
and the said one or more near-infrared receivers, are arranged
linearly, in an array, in an arcuate configuration or in a circular
configuration, to enable a measurement of a parameter of the blood,
such as the blood oxygen content or the relative quantity of
haemoglobin, in different depths, layers or regions from which
myoelectric signals are detected by the said electrode.
5. A sensor arrangement according to claim 1, wherein one or more
electrodes of a myoelectric sensor of the arrangement, or one or
more near-infrared transmitters or one or more near-infrared
receivers of the near-infrared sensor are operated in pulsed mode,
the pulses of which operation overlap or to not overlap as a
function of time, in order to decouple signals, or to couple them,
or to keep the mutual influencing of the signals low, or to exclude
it, or to save energy.
6. A sensor arrangement according to claim 1, wherein signals
indicative of the derived myoelectric activity and the value of
parameter of the blood are not evaluated simultaneously, but
consecutively, wherein in the rest state, in which no muscle
activity is present, the beginning of a contraction, as indicated
by a threshold value of the signal indicative of myoelectric
activity being exceeded, is awaited, and thereupon in the movement
state, in which muscle activity is present, the signal from the at
least one near-infrared sensor indicative of the value of a
parameter of the blood is used to classify the movement, the
contraction or the body part position.
7. A sensor arrangement according to claim 6, wherein following the
classification, a signal from the said at least one
double-differential myoelectric sensor is used to calculate or
obtain for the subsequent processing, a control signal, which is
generally proportional to the muscle force exerted.
8. A method of detecting muscle activity for the control of
technical equipment using a sensor arrangement as claimed in claim
1.
Description
[0001] The invention relates to a combined sensor system for
deriving muscle signals on the skin surface to control, for
example, hand or leg prostheses, or as an input for computers or
other devices.
Prior Art with Sources
[0002] It is known to arrange myoelectric sensors close to muscles
on the skin surface, the sensors detecting the depolarisation
signal emitted to all sides and providing it for further processing
[LUCA, ALTER, HERR09]. It is furthermore known that the
depolarisation signals are overlaid by simultaneously stimulated,
innervated muscles. This effect increases with a growing spacing of
the derivation electrodes and is more pronounced in myoelectric
sensors with single-differential electrodes than in sensors with
double-differential electrodes [FARINA, DELSYS].
[0003] It is further indicated that near-infrared spectroscopy
(NIRS), an active measuring method for the relative measurement of
the blood oxygen content with at least one light transmitter and
one receiver [ASLIN, CHALM], is also suitable for investigating
muscle activity {AKIMA, QUARE, MIURA01 MIURA03]. The combination of
a single-differential myoelectric sensor with a simple
near-infrared sensor, consisting of a light source and a photo
receiver to detect muscle activities is also found in the
literature [HERR10A, HERR10B, HERR11A, HERR11 B]. In the same
literature, it is also shown how the derived signals of the two
sensors can be synchronously combined as a system by a suitable
weighting. A detailed section about the weighted combination of two
features in one time window was disclosed in [HERR10C].
Problem in the Prior Art
[0004] Using the previously known combinations of a myoelectric and
near-infrared sensor it is only possible to detect one region under
the sensor, which cannot be varied during the measurement. The
overlays of the myoelectric signals of a plurality of muscles are
recorded at a recording point and allow the basic distinction
between activity and the rest state and the distinction between
different contraction types. However, there is no information about
the spatial origin of the individual signal components. A
near-infrared sensor, in contrast to this, only detects a spatially
narrowly limited region below the sensor. This sensor type only
indirectly allows an inference of muscle activity, as the blood
quantity, and therefore the quantity of the haemoglobin, is
influenced by a contraction.
[0005] The problem to be solved is therefore that a control signal
proportional to the muscle contraction has to be derived, allowing
a statement about a spatially narrowly limited, well definable
region in the musculature with minimal interferences and without
signal artefacts. The near-infrared signal with a high spatial
resolution cannot be successfully used on its own to control a
technical arrangement or, for example, a prosthesis. The
proportionality between the muscle force exerted and the measured
signal amplitude is lacking for this.
[0006] The problem disclosed is solved in that at least one
double-differential myoelectric sensor and at least one
near-infrared light transmitter and receiver are arranged on the
skin surface, in each case, in order to detect both the muscle
activity and the blood oxygen content, or the relative change in
the quantity of haemoglobin, of the muscle being observed. If the
blood oxygen content or the quantity of haemoglobin in the
observation region changes, less light reaches the near-infrared
receiver from the near-infrared transmitter. The blood oxygen
content can be determined by means of the light intensity, as
explained in the prior art and the contraction inferred. The
penetration depth of the light into the tissue, and therefore the
observation depth, is determined by the spacing apart of the NIR
transmitter and NIR receiver. As different movements have
characteristic time-variant patterns in the EMG and NIR signal, the
movement can be inferred by measuring the two signals and thus, for
example, an arm prosthesis can be controlled successfully and in a
manner close to reality.
[0007] The control signals for an arm, hand or leg prosthesis, for
example, are produced by fusing the sensor signals and by combining
the sensors. The myoelectric signal is used here for the general
recognition of the beginning of a contraction. Following this in
terms of time, in a short time period, the muscle contraction is
classified within a spatially limited region by means of an NIR
signal. When using a plurality of NIR sensors, the reliability of
the classification and moreover also muscle activities in different
muscle regions are distinguished and classified. Following the
classification phase, which is short in terms of time, a movement
or action of the technical arrangement, for example a prosthesis,
can be carried out depending on the myoelectric signal(s).
EMBODIMENTS OF THE INVENTION
[0008] The invention consists of a plurality of electrodes and one
or more near-infrared light sources and one or more optical
receivers, which are arranged in a spatial relationship to one
another. FIG. 1 to FIG. 5 show, by way of example, a plurality of
different arrangements. In general, the electrodes are connected to
one or to more double-differential EMG sensors. The spatial
arrangement of the EMG sensors with respect to NIR sensors and of
the NIR transmitters with respect to the NIR receivers means that
precisely defined regions in the tissue are observed. The figures
in each case show the support face of the sensor from the skin
side.
[0009] FIG. 1 shows a centrally arranged double-differential EMG
sensor, consisting of the electrode pairs (1) and (2) and (2) and
(3) with which the myoelectric activity of the muscles located
therebelow is detected. The EMG sensor consists of three conductive
areas (1), (2) and (3), in our assemblies these are bare metal
contacts with downstream instrument amplifiers of the INA 121 type
from the company Texas Instruments. The near-infrared transmitter,
for example an ultra-bright source (4), such as, for example, a
light-emitting diode or light-emitting diode arrangement in an
encapsulated housing, in our assemblies of the type
L4*730/4*805/4*850-40Q96-I of the producer Epitex Incorporation,
and a sensitive near-infrared receiver (5), for example a
photodiode or a photo transistor with an amplifier connected
downstream or integrated in a housing, in our assemblies of the
OPT101 type from the producer Texas Instruments, surround, singly
or in a multiple configuration, the central sensor arrangement
here.
[0010] FIG. 2 shows, similarly to FIG. 1, an embodiment with a
centrally arranged double-differential EMG sensor, consisting of
the electrode pairs (6) and (7) and (7) and (8), with which the
myoelelectrical activity of the muscles located therebelow is
detected. The EMG sensor consists here of a plurality of
near-infrared transmitters (9) and a plurality of near-infrared
receivers (10). In this embodiment, the transmitters and receivers
are arranged next to the EMG sensor such that the muscle and the
tissue and the blood vessels at a depth along the muscle and
slightly obliquely along the muscle can register the blood oxygen
content, for example the relative quantity of the haemoglobin.
[0011] The embodiment in FIG. 3 allows the detection of the blood
oxygen content, or the quantity of the haemoglobin, at different
depths along or in the muscle. For this purpose, the region with an
NIR transmitter (11) is illuminated and the non-absorbed remaining
light is detected by the sensors (12), controlled in a clocked
manner, simultaneously or consecutively, in order to measure
directly under the EMG sensor at different depths.
[0012] Two or more centrally arranged EMG sensors (13) and (14)
allow the myoelectric signals of a large muscle, for example on the
leg, or a plurality of muscles located next to one another, for
example the chest region, to be detected simultaneously. The
signals of the sensors (13) and (14) are used here either
individually or as correlated signals, for example to reduce the
noise or remove interferences or artefacts. One embodiment is shown
in FIG. 4. As in FIG. 2, a plurality of near-infrared transmitters
(15) and a plurality of near-infrared receivers (16) are also
positioned next to the EMG sensors in this example.
[0013] FIG. 5 shows the embodiment of a combined sensor, consisting
of a plurality of EMG sensors (17) and (18) and a plurality of
near-infrared transmitters (19) and (21) and a plurality of
near-infrared receivers (20). This array arrangement allows the
blood oxygen content, or the relative haemoglobin quantity, to be
measured at different depths and regions either simultaneously or
consecutively.
[0014] In all the arrangements, the myoelectric and the
near-infrared signal are not evaluated simultaneously, but
consecutively. The reason for this is the different signal
properties and the information contained therein, which are based
on various underlying physical effects. The mean value of
myoelectric signal is approximately proportional to the muscle
force exerted. However, inferences about the type of contraction
exerted can hardly be drawn from a single myoelectric signal, as an
overlay of signals of a plurality of muscles occurs, it not being
possible to determine the origin. If, as, for example, in the
forearm, a plurality of muscles are located in the surroundings of
the EMG sensor, a distinction cannot be made as to which one has
carried out a contraction. Owing to the fixed and spatially
delimited observation region of the near-infrared sensor, different
contractions can be inferred with the aid of a sensor. However, the
resulting signal is not proportional to the force developed and
also only supplies meaningful information at the beginning of a
contraction. For this reason, the myoelectric signal is firstly
used for recognition as to whether a muscle contraction is present
at all. The NIR signal cannot be used for this, as it is subject to
interferences due to pressure changes or changes in the surrounding
light. Once a contraction has been recognised, a short time period
can be used in the NIR signal to classify the type of contraction.
As no inferences as to the strength of the contraction are possible
by this, however, the myoelectric signal is used again following
the classification in order to control a movement proportionally,
in other words depending on the muscle force exerted. FIG. 6 shows
a derived EMG and NIR signal for a hand movement over the same time
axis. Once a predefined threshold value (22) has been exceeded, the
movement is determined in the time window for the classification
(23) and the intensity of the movement is determined by the course
of the EMG signal amplitude in the time window (24). The movement
and force control, for example of a hand prosthesis, is determined
therefrom by calculation and by known control engineering
algorithms.
Literature References:
[0015] [ALTER] Alter, Ralph (1966), Bioelectric Control of
Prostheses, Technical Report: Massachusetts Institute of
Technology, Research Laboratory of Electronics [0016] [AKIMA]
Akima, H. (2005), Functional Imaging of Human Skeletal Muscle
During Movement: Implications for Recruitment, Metabolism and
Circulation. International Journal of Sport and Health Science,
Vol. 3, pp. 194-207. [0017] [ASLIN] Aslin, R. and Mehler J. (2005),
Near-infrared spectroscopy for functional studies of brain activity
in human infants: promise, prospects and challenges. Journal of
Biomedical Optics, Vol. 10. pp. 011009. [0018] [CHALM] Chalmers, J.
and Griffiths, P. eds. (2001), Handbook of Vibrational
Spectroscopy. John Wiley & Sons. [0019] [DELSYS] De Luca, C. J.
(2007), A Practicum on the Use of sEMG Signals in Movement
Sciences. Delsys Inc. [0020] [FARINA] Farina, D., Merletti, R.,
Indino, B., Nazzaro, M. and Pozzo, M. (2002), Surface EMG crosstalk
between knee extensor muscles: Experimental and model results.
Muscle & Nerve, 26, pp. 681-695. [0021] [HERR09] Herrmann, S.
and Buchenrieder, K. (2009), Effects of Muscle Fatigue on
Myoelectric Signal and Features in the Time-Domain (2009). African
Journal of Information and Communication Technology. Eingereicht
2009. [0022] [HERR10A] Herrmann, S. and Buchenrieder, K. (2010),
Advanced Control Schemes for Upper Limb Prostheses. Advances in
Medicine and Biology, Nova Science Publishers, Vol. 15, Chapter 17.
[0023] [HERR10B] Herrmann, S. and Buchenrieder, K. (2010),
Development of a Combined Myoelectric and Near-infrared Sensor for
Prostheses Control (2010). Proceedings of the 7th IASTED
International Conference on Biomedical Engineering BioMed 2010, pp.
181-187. [0024] [HERR10C] Herrmann, S. and Buchenrieder, K. (2010),
Fusion of Myoelectric and Near-infrared Signals for Prostheses
Control. Proceedings of the 4th International Convention on
Rehabilitation Engineering & Assistive Technology, Article No:
54. [0025] [HERR11A] Herrmann, S., Attenberger, A. and
Buchenrieder, K. (2011), Prostheses Control with Combined
Near-infrared and Myoelectric Signals. EUROCAST 2011, Part II, LNCS
6928, pp. 602-609. [0026] [HERR11B] Herrmann, S. (2011), Direkte
and proportionate Ansteuerung einzelner Finger von Handprothesen.
Dissertation, University of the Federal Armed Forces, Munich,
Faculty of Information Technology, Graduation date: 25. November
2011. [0027] [LUCA] De Luca, Carlo (2006), Electromyography.
Encyclopedia of Medical Devices and Instrumentation, John Wiley
Publisher, pp. 98-109 [0028] [MIURA01] Miura, H., McCully, K.,
Hong, L., Nioka, S. and Chance, B. (2001), Regional Difference of
Muscle Oxygen Saturation and Blood Volume during Exercise
Determined by Near Infrared Imaging Device. Japanese Journal of
Physiology, Vol. 51, pp. 599-606. [0029] [MIURA03] Miura, H.,
McCully, K. and Chance, B. (2003), Application of
[0030] Multiple NIRS imaging device to the exercising muscle
metabolism. Spectroscopy, Vol. 17, pp. 549-558. [0031] [QUARE]
Quaresima, V., Colier, W., van der Sluijs, M., and Ferrari (2001),
Nonuniform Quadriceps 0.sub.2 Consumption Revealed by Near Infrared
Multipoint Measurements. Biochemical and Biophysical Research
Communications, Vol. 285, pp. 1034-1039.
Captions
[0031] [0032] Abbildung=figure
FIG. 6:
[0032] [0033] Spannung=voltage [0034] Mittelwert=mean value [0035]
Offset bereinigt=offset adjusted [0036] Zeit=time
* * * * *